1. Field of the Invention
The invention relates to a vehicle control apparatus and, more particularly, to a technique for changing any one of the rate of charging of a battery and the rate of discharging of the battery in a hybrid vehicle that runs using driving force from at least one of an internal combustion engine and a motor when vaporized fuel trapped in a canister is introduced to an intake passage of the internal combustion engine.
2. Description of the Related Art
There is known an exhaust gas recirculation (EGR) system that recirculates exhaust gas to an intake passage of an internal combustion engine. Owing to the EGR system, it is possible to reduce unburned fuel, pumping loss, and the like.
Japanese Patent Application Publication No. 2008-155813 (JP-A-2008-155813) describes a vehicle control apparatus that executes high-precision EGR control without causing a shock or a knocking when an internal combustion engine is started during deceleration of a hybrid vehicle.
The vehicle control apparatus described in JP-A-2008-155813 is a control apparatus for a vehicle that uses an internal combustion engine and a rotating electrical machine as drive sources. The vehicle includes the rotating electrical machine and a power split mechanism. The rotating electrical machine is coupled to an output shaft of the internal combustion engine, and generates electric power on the basis of the power of the internal combustion engine. The power split mechanism transmits the power of the internal combustion engine to wheel axles of the vehicle. The power split mechanism splits the power, that is the input from the internal combustion engine, into driving force to the wheel axles and power to the rotating electrical machine.
The internal combustion engine is equipped with an exhaust gas recirculation system. The exhaust gas recirculation system recirculates a part of the exhaust gas of the internal combustion engine to the intake passage of the internal combustion engine via a recirculation valve. The control apparatus includes: a detecting unit; a first control unit and a second control unit. The detecting unit detects a physical quantity related to a vehicle speed. The first control unit controls the recirculation valve, the internal combustion engine and the rotating electrical machine in a first mode when the condition that the vehicle is decelerating and the internal combustion engine is being started holds and then the speed based on the detected physical quantity is higher than or equal to a predetermined speed set in association with a pressure in the intake passage. The second control unit controls the recirculation valve, the internal combustion engine and the rotating electrical machine in a second mode different from the first mode when the above condition holds and then the speed based on the detected physical quantity is lower than the predetermined speed.
With the above described control apparatus, when the speed is higher than or equal to the predetermined speed, it is possible to maintain a state where the throttle valve opening degree is increased. In the state where the throttle valve opening degree is increased, it is possible to suppress an increase in pressure difference between an intake side and an exhaust side. At this time, when the recirculation valve, the internal combustion engine and the rotating electrical machine are controlled in the first mode, it is possible to improve control precision during a transient state of control over the recirculation valve of the exhaust gas recirculation system. Because the precision of EGR control improves, it is possible to suppress occurrence of torque fluctuations or a knocking even when the ignition timing is advanced or even when EGR control is started at the same time with a start of the engine during deceleration of the vehicle. In addition, when the speed is lower than the predetermined speed, the throttle valve opening degree may be decreased. In this case, for example, when the recirculation valve, the internal combustion engine and the rotating electrical machine are controlled in the second mode that is different from the first mode, so as to decrease the degree of change in advance of the ignition timing of the internal combustion engine due to control for increasing the opening degree of the recirculation valve decreases, the degree of change in ignition timing during a transient state of EGR control may be decreased. By so doing, it is possible to execute high-precision EGR control by suppressing occurrence of a knocking. Therefore, even when EGR control is started at the same time with a start of the engine during deceleration of the vehicle, it is possible to suppress occurrence of torque fluctuations or a knocking.
However, when the exhaust gas is recirculated into the intake passage of the internal combustion engine, a negative pressure in the intake passage of the internal combustion engine decreases (pressure increases) as compared with when no exhaust gas is recirculated. Thus, purge of vaporized fuel trapped in the canister may be impaired.